Method of improving the mechanical workability of high chrome steels



Patented Dec. 26, 1933 LMLZM METHOD F HMIPROVIING THE MECHANICAL IIQRKAEHLITY @F HKGH @HROTIE l-llenry A. llle Fries, Albany, N. lz'., assignor to Lndlnrn Steel (Company, Wateryliet, N. 52'... a commotion of New .lersey No Dray ring.

Application March 20, 1020 Serial No. 351,120

3 @lairns.

My invention relates to so-oalled stainless smels and particularly to amethod of improving cer tain characteristics of chromium bearing alloy steels whereby they are rendered easier to forge,

5 machine and grind without in any way detracting from their corrosion resisting properties.

it is well known that alloy steels containing chromium up to 30%, and particularly between 12% and 20%, while highly resistant to corrosion, are nevertheless considerably more dimcult to forge, machine and-grind than regular carbon steels.

It is also well known that a comparatively high sulphur content improves the iorgealoility oi ordinary steels, but the presence of this element in so-called stainless steels, in an amount suficient to appreciably effect the workability thereof, is extremely detrimental to if not destructive of the very property-stainlessness-which prompts the use of such steels.

I find that alloy steels having a high resistance to corrosion and containing up to 30% of chromium may be rendered comparatively easy to .forge, machine and grind, and that their corrosion resisting characteristics are not impaired by the presence of from 0.10% to 0.50% of sulphur provided a small amount of copper, say from 0.20% to 1.20% is also present. The copper not only neutralizes the detrimental effect of the sulphur upon the stainless properties of the steel but materially improves these properties as well as the fo'rgeability.

For example, a steel alloy of the following com= position may be considered as typical, and is very easily forged and machined. Moreover, it

will grind better than regular carbon steel and its corrosion resisting properties are not only unimpaired by the comparatively high sulphur content but actually improved by the addition of the copper:

Carbon Manganese Silicon Chromium Copper Sulphur Phosphorus 0.50% 0.05% 0.25%- 0.35% 0.025 max.

in making this steel, copper matte, an inter mediate product of the copper smelting process, and which is an interrnetallic compound con forming to the formula, ouzsres, maybe added to the steel either in the ladle or in the furnace. The copper matte may be added either in lump or in granular form, and from one to three poiuids v per hundred pounds of steel will not only produce the desired modifications. in the workability of the alloy but will also improve its corrosion resisting properties. What I claim is- 1. The method of improving the forging, machining and grinding properties of an alloy steel containing from 1% to 30% of chromium which comprises incorporating therein sufiicient copper matte to provide a sulphur content of from of copper matte.

HENRY A. DE FRIES. 

